Thin film transistor liquid crystal displays (TFT-LCDs) have been broadly applied in various electronic products such as TV sets, mobile telephones and displays and become dominant in the flat panel display field due to their advantages such as stable pictures, vivid images, radiation elimination, space saving and energy saving; and at present TFT-LCDs with touch functions have been also more and more broadly used.
In prior art, depending on constitution structures, TFT-LCDs with touch functions are classified into: add-on mode touch panels, on-cell touch panels, and in-cell touch panels. For an add-on mode touch panel, the touch panel and the liquid crystal display are produced separately and then attached together to form a liquid crystal display with touch function. Add-on touch panels suffer disadvantages of high manufacturing costs, low light transmission rate, thick module and so on. While for in-cell touch panels, touch electrodes of the touch panel are embedded inside the liquid crystal display, which can reduce the overall thickness of a module and also greatly decrease manufacturing costs of the touch panel, winning much attention from panel manufacturers.
At present, conventional capacitive in-cell touch panels are implemented as illustrated in FIG. 1 by adding additional touch scanning lines 6 and touch sensing lines 7 directly on conventional array substrates, that is, manufacturing two layers of strip-like ITO (Indium Tin Oxides) transparent electrodes that intersect each other in different planes and work as touch driving electrodes and touch sensing lines of the touch panel respectively, and coupling capacitors are formed at the intersections of two ITO transparent electrodes in different planes. The operation process of this kind of touch panel is: detecting voltage signals coupled out by the touch sensing lines via coupling capacitors when touch driving signals are applied to the ITO transparent electrodes serving as touch driving electrodes. In this process, when a finger touches the panel, the body electric field will act on the coupling capacitors to change the capacitance values of relevant coupling capacitors, and in turn change voltage signals coupled out by the touch sensing lines. The location of touch point can be determined depending on the change of voltage signals.
However, the conventional capacitive in-cell touch panels suffer the following problems: capacitances between various electrodes in the liquid crystal cell may influence the coupling capacitances in touch determination and hence influence sensitivity and accuracy of touch determination; in the case where gate lines and data lines for realizing display function and touch scanning lines and touch sensing lines for realizing touch function are interleaving together, not only the aperture ratio of pixels is decreased, but also the difficulty of manufacturing touch liquid crystal displays is increased, and possible process defects will increase accordingly.